Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
import sys
sys.setrecursionlimit(10 ** 6)

H,W=map(int, input().split())  
S=[]
initB=0
for i in range(H):
    s=[0 if j=='.' else 1 if j=='#' else None for j in input()]
    initB+=sum(s)
    S.append(s)
#print(S)
from collections import deque
que=deque([(0,0)])
di=[-1,1,0,0]
dj=[0,0,-1,1]
S[0][0]=1
while que:
    h,w=que.popleft()
    for i,j in zip(di,dj):
        if 0<=h+i<H and 0<=w+j<W and S[h+i][w+j]==0:
            S[h+i][w+j]= S[h][w]+1
            que.append((h+i,w+j))

if S[H-1][W-1]<2:
    print(-1)
else:
    print(H*W-S[H-1][W-1]-initB)
#print(S)